Medical institutions are equipped with a radiographic apparatus configured to emit radiation to image a subject M. Such a radiographic apparatus includes a radiation source 53 and a cassette 54 as illustrated in FIG. 9. The radiation source 53 emits radiation, and the cassette 54 detects the radiation. A top board 52 is provided between the radiation source 53 and the cassette 54. The top board 52 supports the subject M placed thereon.
The radiation source 53 has a collimator 53a attached thereto. The collimator 53a restricts an irradiation area of radiation. The radiation from the radiation source 53 passes through the collimator 53a, whereby the spread of the radiation is restricted. Then the restricted radiation is applied to the subject M.
The radiation source 53 also includes an optical lamp 53p for confirming the irradiation area of the radiation. The optical lamp 53p is disposed behind the collimator 53a, seen from the top board 52, together with a mirror 65. Similarly to the radiation, light beams from the optical lamp 53p pass through the collimator 53a to the top board 52.
When an operator issues a command to turn on the optical lamp 53p prior to irradiation with radiation, the optical lamp 53p is turned on such that visible light beams whose spread is restricted by the collimator 53a are applied to a part of the subject M. Here, the part of the subject M irradiated by the optical lamp 53p corresponds to an area to be irradiated with radiation.
The radiation from the radiation source 53 is not visible light beams. Consequently, an area of the subject M irradiated with the collimated radiation is invisible. Accordingly, the operator turns on the optical lamp 53p prior to the irradiation with radiation, thereby confirming the area of the subject M irradiated with the radiation. Then the operator controls a degree of opening of the collimator 53a while the optical lamp 53p is turned on, achieving control of the irradiation area of the radiation. Japanese Patent Publication No. 2010-094212A describes a construction with such a collimator 53a. 